The invention relates to a tray column with a flowing liquid that has downcomers for transporting the liquid between adjacent trays. The liquid in each downcomer is transported through a plurality of discharge apertures onto a loaded tray. Liquid flowing out of the discharged apertures in the form of jets blends into a regionally divergent flow field when striking the loaded tray. In the flow field there are transverse components of the flow speed with respect to a longitudinal main flow direction.
A tray column contains perforated trays (also known as partition trays) on which in each case a gas phase flowing from the bottom to the top in cross-flow is brought into contact with a liquid phase flowing on the tray for the purpose of an exchange of materials. At least one downcomer is installed in each partition tray for a liquid transport between this tray and a tray lying beneath it which is called a xe2x80x9cloaded trayxe2x80x9d in the following. A tray column is described in U.S. Pat. No. 5,454,989 whose downcomers are made in a special form: discharge apertures are arranged in a base which forms a lower termination of the downcomer. The base is disposed at a spacing above a level which is given by the upper boundary layer of a liquid/gas mixture on the loaded tray. The discharge apertures are limited to a region from which the liquid dispersed in the form of jets has to propagate over the loaded tray partly transversely to a main direction of flow. A further tray column with similar downcomers is known from U.S. Pat. No. 6,250,611.
The propagation of liquid on the loaded tray takes place in an inhomogeneous flow field which has high flow speeds in a central region and low speeds in lateral regions. The inhomogeneities of the flow field mean that the liquid flows through the volume of the exchange of materials with different dwelling times. To obtain an improved exchange of materials, the flow field must be influenced such that a matching of dwelling times results.
It is the object of the invention to further develop the tray column such that an improved exchange of materials is obtained for the individual partition trays by influencing the flow field. This object is attained by arranging guide elements beneath, on and above, or after, discharge apertures and at a spacing from the loaded tray. Each guide element guides the impulse of liquid corresponding to the divergent flow field and thereby contributes to forming the transverse speed components so that the longitudinal component of the flow speed has a largely constant profile in each plane perpendicular to the main flow direction. The discharge apertures are preferably made in different sizes in a graduated fashion so that they are smaller in a central region than in adjacent flank regions. The discharge apertures are arranged in a row, and each guide element is associated with one of the discharge materials. the flow field is regulated so that the dwelling times are matched.
The tray column has downcomers for a transport of a liquid between adjacent trays. The liquid transport takes place in each downcomer through a plurality of discharge apertures onto a loaded tray. Liquid which flows out of the discharge apertures in the form of jets blends into a regionally divergent flow field on striking the loaded tray, said flow field having transverse components of flow speed with respect to a longitudinal main direction of flow. Guide elements are arranged beneath the discharge apertures and at a spacing from the loaded tray. These each guide the liquid impulse in a manner corresponding to the divergent flow field. The formation of the transverse speed components is contributed to by the guide elements such that the longitudinal components of the flow speed in each plane have a largely constant profile perpendicular to the main flow direction. The discharge apertures are preferably formed in different sizes in a graduated fashion to be smaller in a central region than in adjacent flank regions. dr
In the following, the invention will be explained with reference to the drawings.
FIG. 1 is a section of a tray column in accordance with the invention sectioned longitudinally comprising two adjacent partition trays;
FIG. 2 shows flow ratios on and above a partition tray of the tray column shown in FIG. 1;
FIG. 3 shows grate elements of a partition tray;
FIG. 4 shows a grid arrangement with grate elements;
FIG. 5 shows a row of discharge apertures of a downcomer for a tray column in accordance with the invention;
FIGS. 6, 7 show variant embodiments of the discharge apertures;
FIG. 8 is a representation of a design method for the discharge apertures;
FIG. 9 shows a flow breaker with guide elements which is arranged beneath the downcomer on the partition tray; and
FIGS. 10, 11 show two modifications of the downcomer in accordance with the invention.